Washington state has three rather large concrete pontoon bridges (I-90, 520, and Hood Canal). One's being replaced with another concrete pontoon bridge right now. It's being replaced because it doesn't provide enough capacity.

The skills used to build these bridges can then be put to use on any future construction project, be it bridge, building, or dam.

As for lower carbon footprint of the concrete mentioned in the article, it seems laughable compared to the amount of carbon put into the atmosphere by the current Colorado forest fires.

I can see that these are good looking floating docks, and I suppose that they can be used for hydrofoil boats quite well, but I see no way that they could offer much protection to a boat in a typhoon, or any big storm. Like the comments say, objects bang togather in storms, and damage is done by that banging.

Or is the plan that these floating docks are big and heavy enough to shield the catamaron boats? That would be interesting indeed. I would like to see pictures of that.

The alternative cement material used for ballast is an interesting concept, and I am not aware that it is used in this part of the country, (southeast Michigan), so it would be a good topic for a writeup some time in the future.

A serious lack of details. The composite seems to be the beams, rails and calling them maintaince free is a joke. The coating can and will be damaged a lot and likely the composite part too from boats ramming it, etc.

How do they pultrude Vinyl ester resin which normally takes many minutes to go from liquid to solid. Some engineering details would be nice.

Recycling is easy, just heat to 1000F and use the gas made from the resin. Recycling FG just gives you sand so not worth it.

Racking in a cyclone is likely to break at the bolt holes/point loads much more easy than alum would.

What is the 'concrete' actually used for?

What are the floats, decks made of? Is it the larger rectangles under the deck beams? If so not much floatation.

Leaving boats at a dock in a cyclone/hurricane is very problematic and most docks in Fla say in a hurricane you must move them away to keep from damaging the docks or sinking of the boats from pounding into the docks. BTDT many times. Made a lot of money repairing same afterward.

I take my boats to canals or mangroves and tie them with long lines in the middle away from anything hard. I've been though a lot of them caring for my boats and others professionally. You need 15-50' from anything hard depending on tidal surge, range and bost size.

A well done concrete dock floats will last centuries as they get stronger with age. Ask anyone trying to get rid of a concrete ship. The only way is to sink it. For a floating island the only viable material is concrete.

ervin, as the article states, the pontoon is made of composites, not concrete, and is built for cyclone conditions. Lots of sub-par construction occurred in the US in the 1970s. Since then, the building codes in many regions of the US have changed, due in part to earthquake and hurricane-caused disasters. I suspect something similar has occurred in Australia.

naperlou, good questions. There are some efforts underway to develop recycling methods for composites, most notably Boeing: http://www.designnews.com/document.asp?doc_id=235280 That said, I'm not familiar with the situation in Australia, or whether the marina industry has thought of that problem yet, since the materials last so long.

Beth, the pontoon project is a custom job, so it's not surprising that the partners didn't mention specific cost details. Since, as we stated, the composite practically eliminates maintenance and doubles the design life, I suspect the overall cost of ownership is lower.

I think this is a bad use of composite. I have not run the numbers yet. But I live in Florida. Lots of storms right? Guess what? There are floating docks here in Florida from the 70's and they were cheaply made with yours truly "Concrete". They are big, chunky, heavy, durable, and cheap. If they break they sink. Keep in mind floating things in a hurricane can be problematic considering they can be picked up and flung at something so a good bit of mass is always a plus. Yes concrete blocks underwater could become potential debris for structures downstream too it's hard to gauge what's best. However it is know that cheap always beats good looking. I will have to go with concrete on this one... At least until data point the other direction.

Ann, this is yet another interesting use of composites. I wonder, though about the environmental impact. In discussing the ballast, the EFC, it seems that the builders were paying attention to the environmental impact of their structure. That is good. The EFC uses byproduct of other industrial processes, thus extending the use of the raw materials. I have seen the amount of fly-ash produced by a small coal fired plant. Usually it is burried in the coal mine. Now, I expect that this structure will have a lower life cycle cost becuase of the lower maintenance. As Beth asked, what about the initial cost (is it comparable)? The other environmental question is, what happens to the structure when it is finally retired. Can the materials be recycled? One thing about steel is that it can, indefinately. Once refined, it is indistinguishable from the original (think steel mini-mills). Composites, on the other hand, can generally only be recycled into lower level forms. That is my assumption. Do you have any information on that aspect?

Looks like a pretty standard dock, albeit it one in much better shape that most floating platforms, which I suppose speaks to the utility of the composite materials in harsh marine environments. So while the maintenance costs are reduced and the lifecycles might be longer, does the choice of composite materials over metal up the cost significantly?

Industrial workplaces are governed by OSHA rules, but this isn’t to say that rules are always followed. While injuries happen on production floors for a variety of reasons, of the top 10 OSHA rules that are most often ignored in industrial settings, two directly involve machine design: lockout/tagout procedures (LO/TO) and machine guarding.

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